1. Field of the Invention
This invention relates to an axial flow fan with auxiliary blades wherein the auxiliary blades are arranged in a most suitable manner relative to the fan blades.
2. Description of the Prior Art
Heretofore, some of the conventional axial flow fans have been provided with auxiliary blades on the surface of the fan blades. However, it was found to be difficult to form centrifugal flows of air positively in the axial flow fan, and none of the fans were found to be satisfactory from the viewpoints of aerodynamic performances such as the output air flow blowing efficiency and noise level. While centrifugal flows of air could be positively provided in our axial flow fan with auxiliary blades Japanese Utility Model Application Numbers 58988/1975, 58989/1975, 58990/1975, 152509/1975, 23737/1976, Patent Application Numbers 153066/1976, 153067/1976, and 153068/1976), further improvement can be expected in the air flow rate noise level, and other aerodynamic performances so that an optimum operating condition is realized.
In other words, the present invention has been developed after a series of experiments, conducted under visualization and analyses, for the purpose of obtaining an optimum positional relation of the auxiliary blades relative to the fan blades of the axial flow fan.